/*

 * Copyright 1997-2005 Sun Microsystems, Inc.  All Rights Reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,

 * CA 95054 USA or visit www.sun.com if you need additional information or

 * have any questions.

 *

 */

// A symbolOop is a canonicalized string.

// All symbolOops reside in global symbolTable.

// See oopFactory::new_symbol for how to allocate a symbolOop

class symbolOopDesc : public oopDesc {

  friend class VMStructs;

 private:

  unsigned short _length; // number of UTF8 characters in the symbol

  jbyte _body[1];

  enum {

    // max_symbol_length is constrained by type of _length

    max_symbol_length = (1 << 16) -1

  };

 public:

  // Low-level access (used with care, since not GC-safe)

  jbyte* base() { return &_body[0]; }

  // Returns the largest size symbol we can safely hold.

  static int max_length() {

    return max_symbol_length;

  }

  static int object_size(int length) {

    int size = header_size() + (sizeof(unsigned short) + length + HeapWordSize - 1) / HeapWordSize;

    return align_object_size(size);

  }

  int object_size() { return object_size(utf8_length()); }

  int byte_at(int index) const {

    assert(index >=0 && index < _length, "symbol index overflow");

    return ((symbolOopDesc*)this)->base()[index];

  }

  void byte_at_put(int index, int value) {

    assert(index >=0 && index < _length, "symbol index overflow");

    ((symbolOopDesc*)this)->base()[index] = value;

  }

  jbyte* bytes() { return base(); }

  int utf8_length() const { return _length; }

  void set_utf8_length(int len) { _length = len; }

  // Compares the symbol with a string

  bool equals(const char* str, int len) const;

  // Three-way compare for sorting; returns -1/0/1 if receiver is </==/> than arg

  // note that the ordering is not alfabetical

  inline int fast_compare(symbolOop other) const;

  // Returns receiver converted to null-terminated UTF-8 string; string is

  // allocated in resource area, or in the char buffer provided by caller.

  char* as_C_string() const;

  char* as_C_string(char* buf, int size) const;

  // Use buf if needed buffer length is <= size.

  char* as_C_string_flexible_buffer(Thread* t, char* buf, int size) const;

  // Returns a null terminated utf8 string in a resource array

  char* as_utf8() const { return as_C_string(); }

  char* as_utf8_flexible_buffer(Thread* t, char* buf, int size) const {

    return as_C_string_flexible_buffer(t, buf, size);

  }

  jchar* as_unicode(int& length) const;

  // Treating this symbol as a class name, returns the Java name for the class.

  // String is allocated in resource area if buffer is not provided.

  // See Klass::external_name()

  const char* as_klass_external_name() const;

  const char* as_klass_external_name(char* buf, int size) const;

  bool object_is_parsable() const {

    return (utf8_length() > 0 || (oop)this == Universe::emptySymbol());

  }

  // Printing

  void print_symbol_on(outputStream* st = NULL);

};

// Note: this comparison is used for vtable sorting only; it doesn't matter

// what order it defines, as long as it is a total, time-invariant order

// Since symbolOops are in permSpace, their relative order in memory never changes,

// so use address comparison for speed

int symbolOopDesc::fast_compare(symbolOop other) const {

 return (((uintptr_t)this < (uintptr_t)other) ? -1

   : ((uintptr_t)this == (uintptr_t) other) ? 0 : 1);

}